package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.ObjectUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.service.IUserService;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.security.Key;
import java.util.*;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.BLOG_LIKED_KEY;
import static com.hmdp.utils.RedisConstants.FEED_KEY;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {

    @Resource
    private IUserService userService;

    @Resource
    private StringRedisTemplate stringRedisTemplate;


    @Override
    public Result queryBlogById(Long id) {
        Blog blog = this.getById(id);
        if (blog == null) {
            return Result.fail("该笔记不存在");
        }
        queryBlogUser(blog);
        isBlogLiked(blog);
        return Result.ok(blog);
        
    }

    private void isBlogLiked(Blog blog) {
        UserDTO userDTO = UserHolder.getUser();
        if (userDTO == null) {
            return;
        }
        //1.获取当前用户id
        Long id = UserHolder.getUser().getId();
        //2. 拼接key
        String key = "blog:liked" + id;
        Double score = stringRedisTemplate.opsForZSet().score(key, id.toString());
        blog.setIsLike(score != null);
    }

    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog -> {
            this.isBlogLiked(blog);
            this.queryBlogUser(blog);});
        return Result.ok(records);
    }



    @Override
    public Result likeBlog(Long id) {
        //1.先获取用户id
        Long userId = UserHolder.getUser().getId();
        //2. 拼接redis key
        String key = BLOG_LIKED_KEY + id;
        //3. 看该用户是否对当前浏览的笔记点赞过
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        //为false说明未对该笔记点赞过
        if (ObjectUtil.isNull(score)) {
            boolean updateSuccess = update().setSql("liked = liked + 1").eq("id", id).update();
            //如果点赞成功讲该用户的id添加到redis的博客笔记点赞集合当中
            if (updateSuccess) {
                stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());
            }
        }else {
            //对该笔记点赞过
            boolean updateSuccess = update().setSql("liked = liked - 1").eq("id", id).update();
            //如果点赞成功讲该用户的id添加到redis的博客笔记点赞集合当中
            if (updateSuccess) {
                stringRedisTemplate.opsForZSet().remove(key,userId.toString());
            }
        }
        return Result.ok();
    }

    @Override
    public Result queryBlogLikes(Long id) {
        //1.拼接key
        String key = BLOG_LIKED_KEY + id;
        //2. 获取top5
        Set<String> top5 = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        //3. 如果为空代表还没有用户给该笔记点赞 返回空集合
        if (top5 == null || top5.isEmpty()) {
            return Result.ok(Collections.EMPTY_LIST);
        }
        //4. 解析出集合中的用户id
        List<Long> ids = top5.stream().map(Long::valueOf).collect(Collectors.toList());
        String idStr = StrUtil.join(",", ids);
        //5. 根据id去数据库中查找这些用户
        List<UserDTO> userDTOList = userService.query()
                .in("id", ids)
                .last("ORDER BY FIELD(id," + idStr + ")")
                .list()
                .stream().map(user ->
                        BeanUtil.copyProperties(user, UserDTO.class)
                ).collect(Collectors.toList());
        return Result.ok(userDTOList);
    }

    @Override
    public Result queryBlogByUserId(Integer current, Long id) {
        Page<Blog> page = query().eq("user_id", id).page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        return Result.ok(page.getRecords());
    }
    

    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        //1.获取当前用户id
        Long userId = UserHolder.getUser().getId();
        //2.拼接key
        String key = FEED_KEY + userId;
        //3.从redis中获取
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet().reverseRangeByScoreWithScores(key, 0, max, offset, 2);
        //4. 判断是否为空 为空说明关注的用户还没有发布最新笔记
        if (typedTuples == null || typedTuples.isEmpty()) {
            return Result.ok();
        }
        //5. 遍历集合获取id和minTime
        // 存储id的集合
        List<Long> ids = new ArrayList<>(typedTuples.size());
        // 上次滚动分页的结束点
        Long minTime = 0L;
        int os = 1;
        for (ZSetOperations.TypedTuple<String> typedTuple : typedTuples) { // 5 4 4 2 2
            ids.add(Long.valueOf(Objects.requireNonNull(typedTuple.getValue())));
            long time = typedTuple.getScore().longValue();
            if (time == minTime) {
                os++;
            }else {
                minTime = time;
                os = 1;
            }
        }
        String StrIds = StrUtil.join(",", ids);
        List<Blog> blogs = query().in("id",ids).last("ORDER BY FIELD(id," + StrIds + ")").list();
        for (Blog blog : blogs) {
            queryBlogUser(blog);
            isBlogLiked(blog);
        }
        ScrollResult scrollResult = ScrollResult.builder()
                .list(blogs)
                .offset(os)
                .minTime(minTime)
                .build();
        return Result.ok(scrollResult);
    }

    private void queryBlogUser(Blog blog) {
        UserDTO userDTO = UserHolder.getUser();
        if (userDTO == null) {
            return;
        }
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }
}
